mmc: sdhci-of-esdhc: add delay between tuning cycles

It's observed that eSDHC needed delay between tuning cycles for
HS200 successful tuning. This patch is to set 1ms delay for that.

Signed-off-by: Yangbo Lu <yangbo.lu@nxp.com>
Acked-by: Adrian Hunter <adrian.hunter@intel.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>